The system layer affects how the system interacts with a SAN Volume Controller
IBM Spectrum Virtualize™
system and other external Storwize® family
systems.
An IBM®
Storwize family system is in either the
replication layer or the storage layer.
Differences between the storage layer and the replication
layer
Table 1 compares the characteristics
and requirements of storage layer and replication layer systems.
Table 1. Comparison of storage layer and replication layer systems| Storage layer |
Replication layer |
|---|
- The system can
complete Metro Mirror and Global Mirror replication with other
storage-layer systems.
- The system can provide
external storage for replication-layer systems or a SAN Volume Controller
system.
- The system cannot use
another Storwize family system that is
configured with storage-layer as external storage.
|
- The system can
complete Metro Mirror and Global Mirror replication with other
replication-layer systems or a SAN Volume Controller
system.
- The system cannot
provide external storage for a replication-layer system or a SAN Volume Controller
system.
- The system can use
another Storwize family system that is
configured with storage-layer as external storage.
|
A Storwize family system is in the storage layer by default, but the layer can be changed. For example, you might
want to change a Storwize V7000 system to a
replication layer to complete Global Mirror or Metro Mirror replication with a SAN Volume Controller
system.
Changing the layer of a Storwize family system
To change the storage layer of an existing Storwize system with internal storage
before you add a second system into the SAN zone, you do not need to stop I/O operations.
However, if the system has Fibre Chanel (FC) connections to another
Storwize family or SAN Volume Controller
system in the SAN fabric, I/O
operations must be stopped temporarily. In this scenario, the FC ports must be disabled (for
example, by unplugging all the FC ports, changing zoning, disabling switch ports) before you change
the system layer. Then, you must re-enable the FC ports.
Before you change the system layer, the following conditions must be met:
- No host object can be configured with worldwide port names (WWPNs) from a Storwize family system.
- No system partnerships can be defined.
- No Storwize family system can be
visible on the SAN fabric.
To change the layer of a system, follow these general steps:
- Use the lssystem command to
check the current system layer.
- Configure SAN zoning so that the
system whose layer you are changing is not visible to any other system.
- Ensure that all other configuration requirements are met.
- Run the detectmdisk command to ensure that the system detects any fabric changes
that were done in step 3.
- Enter the one of the following commands to switch the system to the appropriate layer.
- If the SAN configuration was changed in step 2,
restore the normal SAN configuration.
- Run the detectmdisk command to update the list of MDisks.